Polyelectrolyte-surfactant　complexes　(PESCs)　were　fabricated　through　the　interaction　of　poly(acrylic　acid)　and　four　different　cationic　surfactants　or　their　mixtures.　PESC　membranes　were　prepared　by　solution　casting　method　and　were　applied　in　ethanol　recovery　from　aqueous　solution　via　pervaporation.　Elemental　analysis　(EA),　Fourier　transform　infrared　spectroscopy　(FTIR),　water　contact　angle　(CA)　measurement,　differential　scanning　calorimetry　(DSC)　and　X-ray　scattering　were　employed　to　characterize　the　composition,　structure　and　properties　of　PESCs.　The　results　reveal　that　the　investigated　PESCs　are　similar　in　hydrophobicity　but　different　in　hierarchical　nanostructures.　In　separating　5　wt%　ethanol/water　mixture,　PESC　membranes　with　high　crystallinity　will　have　both　low　flux　and　ethanol　selectivity　because　of　the　high　packing　density　and　low　permeability　of　crystalline　regions.　Meanwhile,　the　hierarchical　nanostructures　of　PESC　membranes　change　under　pervaporation　environment　as　was　revealed　by　in　situ　synchrotron　radiation　X-ray　scattering　measurement.　That　is,　the　crystalline　region　could　melt　at　high　temperature　in　swelling　state,　thus　consequently　enhancing　the　ethanol　selectivity.